FXa-α2-Macroglobulin Complex Neutralizes Direct Oral Anticoagulants Targeting FXa In Vitro and In Vivo

Area of Science:

• Biochemistry
• Pharmacology
• Hematology

Background:

• Direct oral anticoagulants (DOACs) are increasingly prescribed.
• Approved antidotes exist for dabigatran but not for Factor Xa (FXa) inhibitors (xabans).
• Need for a safe and effective antidote for FXa inhibitors is critical.

Purpose of the Study:

• To investigate the potential of a complex between Gla-domainless FXa and α2-macroglobulin (GDFXa-α2M) as an antidote for FXa inhibitors.
• To evaluate the efficacy and safety of GDFXa-α2M in neutralizing xabans in vitro and in vivo.

Main Methods:

• Formation of GDFXa-α2M complex by incubating purified α2M with GDFXa.
• Assessment of apixaban and rivaroxaban affinity for GDFXa-α2M.
• In vitro testing using clot waveform assay and rotational thromboelastometry.
• In vivo studies in mice to evaluate efficacy, half-life, and pro-thrombotic potential.

Main Results:

• GDFXa-α2M showed only slightly decreased affinity for apixaban and rivaroxaban compared to FXa.
• GDFXa-α2M effectively neutralized rivaroxaban and apixaban in vitro without affecting normal coagulation.
• In vivo, GDFXa-α2M significantly reduced rivaroxaban-induced bleeding and blood loss.
• No increase in D-dimer or thrombin-antithrombin complex formation indicated a lack of pro-thrombotic activity.

Conclusions:

• GDFXa-α2M is a promising candidate for neutralizing FXa inhibitors (xabans).
• This complex demonstrates efficacy in reversing anticoagulant effects without inducing thrombosis.
• GDFXa-α2M represents a potential new therapeutic strategy for managing bleeding complications associated with DOACs.